Descriptions

During 1973 data was collected to analyze the seasonal variations of the tidal dynamics, water quality and sediments of the Alsea
Estuary. A summary of historical information with a list of all
known alterations to the estuary was made. A complete physical
description, including the geographical setting and mixing classification of the estuary, was done.
Times of high and low water and tidal ranges at three locations
were measured. Tide measurements made at Waldport indicated that the
published tide predictions for that location were reliable. At a
location upstream of the estuary embayment noticeable damping of the
tidal wave amplitude was detected during periods of high river flow
and high tidal range. High water lag times were found to decrease
during periods of high river flow, but low water lag times were
unaffected by river flow. The tide motion was found to be a damped,
partially standing wave, which altered its behavior according to the
volume of water in the estuary.
The high and low tide water quality parameters of salinity,
temperature, dissolved oxygen, turbidity and pH were measured at 10
to 18 locations during each season to determine any seasonal changes
in them. The parameters at a given location were found to be a function of river flow and tidal range.
Winter and summer sediment samples were analyzed for grain size
distribution, volatile solids and porosity. The sediments from the
main channel exhibited characteristics of a high velocity regime and
those of the north channel, a low velocity regime.